Basic electrical engineering introduction, Slides of Electrical and Electronics Engineering

Download Basic electrical engineering introduction and more Slides Electrical and Electronics Engineering in PDF only on Docsity!

ELEM 212

Basic Electrical Engineering

Objectives

• To be able to describe the relationship

between voltage, current, resistance (Ohms

Law)

• Know the operating principles of AC – DC

equipment

• Know the basic electrical blueprint, house

wiring and lighting and electrical safety.

• One form of energy can be converted

into another

Example:

Oil - Heat

Water – Steam

Turbine – Mechanical Energy

Generator – Electrical Energy

What is electricity?

Matter Anything that has mass and occupy space Molecule The smallest particle of any compound that retains the original characteristics Atom Composed of sub atomic particles of electrons, protons and neutrons.

• Matter can be classified into two groups: Elements or Compound

• Atoms of different elements differ from one another in the number of electrons and protons they contain (Fig. 1-2). In its natural state, an atom of any element contains an equal number of electrons and protons. Since the negative (-) charge of each electron is equal in magnitude to the positive (+) charge of each proton, the two opposite charges cancel. An atom in this condition is electrically neutral, or in balance (Fig. 1-2).

Coulomb

The magnitude of electric charge a body possesses is determined by the number of electrons compared with the number of protons within the body. The symbol for the magnitude of the electric charge is Q, expressed in units of coulombs (C). A charge of one negative coulomb, - Q, means a body contains a charge of 6.25 x 10 18 . 1 C = 6.25 x 10 18 electrons.

Electric Field It is the region around the charge particle within which the other charges experience the force of attraction and repulsion.

Potential Difference

The potential difference between points A and B, V B

– V

A , is defined to be the change in potential energy of a charge q moved from A to B, divided by the charge. Units of potential difference are joules per coulomb, given the name volt (V) after Alessandro Volta. 1V= 1 J/C

The force of its electrostatic field, an electric charge has the ability to do the work of moving another charge by attraction or repulsion. The ability of a charge to do work is called its potential. In simple terms potential difference is voltage. What makes the charge flow?

Current The movement or the flow of electrons is called current. To produce current, the electrons must be moved by a potential difference. Current is represented by the letter symbol I. The basic unit in which current is measured is the ampere (A). 1 A = 1 C/s I = Q / T

Current Flow

• In a conductor, such as copper wire, the free electrons are charges that can be forced to move with relative ease by a potential difference. If a potential difference is connected across two ends of a copper wire , the applied voltage (1.5 V) forces the free electrons to move.